/****************************************************************************
 * arch/x86_64/include/syscall.h
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/* This file should never be included directly but, rather, only indirectly
 * through include/syscall.h or include/sys/sycall.h
 */

#ifndef __ARCH_X86_64_INCLUDE_SYSCALL_H
#define __ARCH_X86_64_INCLUDE_SYSCALL_H

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <stdint.h>

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* Configuration ************************************************************/

#ifndef CONFIG_BUILD_FLAT
#  define CONFIG_SYS_RESERVED 4
#else
#  define CONFIG_SYS_RESERVED 0
#endif

/* system calls */

#ifndef CONFIG_BUILD_FLAT
/* SYS call 0:
 *
 * void up_task_start(main_t taskentry, int argc, char *argv[])
 *        noreturn_function;
 */

#  define SYS_task_start            (0)

/* SYS call 1:
 *
 * void up_pthread_start((pthread_startroutine_t startup,
 *                        pthread_startroutine_t entrypt, pthread_addr_t arg)
 *        noreturn_function
 */

#  define SYS_pthread_start         (1)

/* SYS call 2:
 *
 * void signal_handler(_sa_sigaction_t sighand,
 *                     int signo, siginfo_t *info,
 *                     void *ucontext);
 */

#  define SYS_signal_handler        (2)

/* SYS call 3:
 *
 * void signal_handler_return(void);
 */

#  define SYS_signal_handler_return (3)

#endif /* !CONFIG_BUILD_FLAT */

/****************************************************************************
 * Public Types
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

#ifndef __ASSEMBLY__
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif

/* SWI with SYS_ call number and six parameters */

static inline uintptr_t sys_call6(unsigned int nbr, uintptr_t parm1,
                                  uintptr_t parm2, uintptr_t parm3,
                                  uintptr_t parm4, uintptr_t parm5,
                                  uintptr_t parm6);

/* SWI with SYS_ call number and no parameters */

static inline uintptr_t sys_call0(unsigned int nbr)
{
  return sys_call6(nbr, 0, 0, 0, 0, 0, 0);
}

/* SWI with SYS_ call number and one parameter */

static inline uintptr_t sys_call1(unsigned int nbr, uintptr_t parm1)
{
  return sys_call6(nbr, parm1, 0, 0, 0, 0, 0);
}

/* SWI with SYS_ call number and two parameters */

static inline uintptr_t sys_call2(unsigned int nbr, uintptr_t parm1,
                                  uintptr_t parm2)
{
  return sys_call6(nbr, parm1, parm2, 0, 0, 0, 0);
}

/* SWI with SYS_ call number and three parameters */

static inline uintptr_t sys_call3(unsigned int nbr, uintptr_t parm1,
                                  uintptr_t parm2, uintptr_t parm3)
{
  return sys_call6(nbr, parm1, parm2, parm3, 0, 0, 0);
}

/* SWI with SYS_ call number and four parameters */

static inline uintptr_t sys_call4(unsigned int nbr, uintptr_t parm1,
                                  uintptr_t parm2, uintptr_t parm3,
                                  uintptr_t parm4)
{
  return sys_call6(nbr, parm1, parm2, parm3, parm4, 0, 0);
}

/* SWI with SYS_ call number and five parameters */

static inline uintptr_t sys_call5(unsigned int nbr, uintptr_t parm1,
                                  uintptr_t parm2, uintptr_t parm3,
                                  uintptr_t parm4, uintptr_t parm5)
{
  return sys_call6(nbr, parm1, parm2, parm3, parm4, parm5, 0);
}

static inline uintptr_t sys_call6(unsigned int nbr, uintptr_t parm1,
                                  uintptr_t parm2, uintptr_t parm3,
                                  uintptr_t parm4, uintptr_t parm5,
                                  uintptr_t parm6)
{
  uint64_t ret;

  /* Registers modified by syscall instruction:
   *   RCX = RIP
   *   R11 = RFLAGS
   *   RIP = IA32_LSTAR (x86_64_syscall_entry)
   */

  __asm__ volatile
  (
    "movq %1, %%rax\n"
    "movq %2, %%rdi\n"
    "movq %3, %%rsi\n"
    "movq %4, %%rdx\n"
    "movq %5, %%r10\n"
    "movq %6, %%r8\n"
    "movq %7, %%r9\n"
    "syscall\n"
    "movq %%rax, %0\n"
    : "=r"(ret)
    : "rm"(nbr), "rm"(parm1), "rm"(parm2),
      "rm"(parm3), "rm"(parm4), "rm"(parm5),
      "rm"(parm6)
    : "memory", "rcx", "r11"
  );

  return ret;
}

#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif

#endif /* __ARCH_X86_64_INCLUDE_SYSCALL_H */
